1. Field of the Invention
The present invention relates to a series of benzoxazine containing propargyl group and a method for preparing the same. The compound may be used as flame resistant material because of containing phosphorus, and may also provide enhanced thermal stability because of introducing propargyl group to increase cross-linked point.
2. Description of Related Art
Phenol formaldehyde resin is made from condensing phenol compounds and aldehyde compounds, wherein the phenol formaldehyde resin made from condensing phenol and formaldehyde is the most important resin. The raw materials of phenol formaldehyde resin are easy to be obtained, low water absorption, excellent workability and have the superior properties which may satisfy the functions after resin cured, so that the phenol formaldehyde resin is widely used in the related field of livelihood, electronics, military, and architecture, etc. Benzoxazine resin which is developed recent years also belongs to one of the phenol formaldehyde resins, and is characterized by open ring curing after heating monomer without leaking water or other side effects while curing. Hence, benzoxazine resin has better workability than phenol formaldehyde resin.
Introducing different functional groups into benzoxazine monomer may render improved properties corresponding to that of the original one. Introducing propargyl functional group is an effective method to provide more cross-linked points, to increase glass transition temperature, and also to improve the thermal stability. However, introducing propargyl functional groups requires much complicated steps. In the prior reference, Takeichi[1] et al use three steps of (1) nucleophilic substitution reaction, (2) reducing NO2 reaction, and (3) generating benzoxazine to introduce propargyl group into benzoxazine monomer. Yagci, Y[2] et al also develop another method in the same year, however the method requires four steps of (1) using acetic acid to protect NH2 group, (2) nucleophilic substitution reaction, (3) forming NH2 group, and (4) generating benzoxazine to synthesize benzoxazine containing proparyl group. Besides the aforementioned two, Ishida[3][4] et al use a similar method to prepare it as well.
To sum up the above references, most of the references indicate that while adding propargyl bromide, limiting propargyl bromide to react with OH group only by NH2 substitution in order to protect NH2. Then, using reduction to generate NH2 group, and NH2 group reacts with formaldehyde and phenol to form benzoxazine. However, the procedures are too complicated, our team develops a simple pattern to synthesize benzoxazone containing propargyl functional group. First, protect NH2 group by forming the structure of benzoxazine, and then adding propargyl bromide to react with OH group to generate benzoxazine containing propargyl functional group. We do not need complicated steps to synthesize it through such pattern.